Connect your phone to your computer through bluetooth or a usb cable.
Once set up go to your control panel -> Phone & Modem Options -> Modems Tab - > Highlight the modem that was set up when your phone installed it. -> Click the Properties Button -> Advanced Tab and then paste the following in the Extra initialization commands box
AT+CGDCONT=1,"IP","EPC.TMOBILE.COM" (Only to be used in areas that support EDGE Data and also a phone that supports EDGE, with this setup there is no need for proxy, it is unrestricted) Proof I've made video calls on Skype while in the car and the call was fairly clear on both ends. It seems to disconnect however after about 5 - 10 mins of major use. For simple tasks like web browsing and IMs its perfect.
AT+CGDCONT=1,"IP","wap.voicestream.com" (GPRS connection, also must use a proxy address with your browsers
T-Mobile Proxy: 184.108.40.206~Mom with a Scattered Mind~
T-Mobile's Proxy Port: 8080
If you have any other questions feel free to ask and I will try and help you.
Also if you visit this page Howard Forums Wiki you should find very helpful information.
I jsut did this post to spell it out in more plain english